Tensioning apparatus



March 10, 1936. FRENCH 2,033,625

TENSIONING APPARATUS Filed March 50, 1935 WWW INVENTOR.

Jr/mmEVFf/ E/vcm ATTORNEYS Patented Mar. 10, 1936 UNITED STATES PATENTOFFICE TENSIONING APPARATUS Application March 30,

9 Claims.

My present invention relates to an electric tensioning device forsupplying a substantially constant tension to strip or filamentarymaterial drawn under tension at variable speeds. The invention relatesmore particularly to compensating means for electric tensioning devicessuch as shown in my Patent No. 1,968,251 granted July 31, 1934, wherebya tension applying electric current may be varied or compensated tomaintain a substantially constant torque and tension under varyingspeeds of the material subjected to tension.

In the apparatus of the above mentioned Patent 1,968,251 the tension andtension controlling apparatus comprises a circuit containing a motor,the armature of which is driven by the passage of the tensioned materialin a direction opposite to the torque applied by the current in thecircuit. The direction of the torque imposed by the electric current onthe motor being opposite to the direction of movement of the tensionedmaterial, imposes a tension on the latter directly proportional to thetorque of the motor. Al though the current imposes a predeterminedconstant torque on the motor when the armature of the latter is heldstationary, this torque increases when the armature is rotated in adirection opposite to the torque and thus increases the tension as thespeed of the tensioned material increases.

This increase in torque is due to the building up of an electro-motiveforce which has the same effect as a reduction in the resistance throughthe motor armature and thus permits the passage of an increased currentthrough the motor.

In the normal operation of a motor the current through the armature isgreatest, and the greatest torque is accordingly obtained, when thearmature is stationary. As the armature is driven or rotated by theapplied torque it builds up a reverse or back electro-motive force whichopposes that of the driving circuit and thus decreases the currentthrough the armature. When the armature is driven in a reverse directionagainst the torque by the passage of the tensioned material, the efl'ectis just the reverse, inasmuch as the rotation of the armature isreversed, and an electro-motive force is generated which is additive tothat of the driving circuit. The increased current in the armaturecaused by this additive electro-motive force increases the torque, whichincreases with the armature current, and thus increases the tension.

My invention provides a means whereby this increased armature currentand resultant in- 1935, Serial No. 13,879

crease in torque and tension may be compen-- sated and the tension heldconstant or controlled and, moreover, whereby several tensioning devicesmay be controlled and held constant by unitary means.

The various features of my invention are illustrated, by way of example,in the accompanying drawi in which- Figs. 1 and 2 are side and frontviews, respectively, of tensioning mechanisms embodying a preferred formof the invention, and I Fig. 3 is a diagrammatic electric diagram of thetension controlling circuits and mechanisms.

In my invention I provide means controlled by the passage of thetensioned material to decrease the voltage or electro-motive force ofthe current supplied to the tensioning motor as the speed of passage ofthe tensioned material increases, and thereby to counteract the effectof the additive electroemotive force generated by the reverse rotationof the tensioning motor armature. Inasmuch as the current may besupplied to a number of tensioning motors in parallel, my control meansmay be applied to the simultaneous control of a number of tensioningmotors supplying material at similar speeds to a common object as, forexample, a number of strips for wrapping onto a core or cable, or anumber of strands of textile or other material supplied to form a threador cable.

In my circuit I provide means whereby the tension may be adjusted forany particular speed with the material at rest. I also provide meanswhereby the compensating effect may be adjusted so as to increase ordecrease the compensation of current, and thus to tension the materialin a controlled manner in a predetermined relation to its speed.

In Fig. 1 an embodiment of the invention is shown, by way of example, asapplied to the tensioning mechanism shown in Patent 1,968,251 forwrapping a strip of paper or other material onto a rotating core I froma supply reel 2. In this embodiment there is a relative rotation of thecore and the supply reel, either by rotating the supply reel about thecore as described in the patent to wrap strip 3 from the reel about thecore, or by holding the reel 2 stationary and rotating the core I so asto wind the strip about the core. For this purpose the strip 3 is drawnfrom the reel 2 about an idle roller 4 carried on pivoted arms 6 andheld by a spring I tightly against the reel 2, and then passes over atensioning roller 8 which is connected to the armature of the tensioningmotor 9 either directly or through speed change mechanism. The strip isthen drawn about succeeding idler rollers l0 and II as described in theabove mentioned patent, and wrapped on the core I.

Current is supplied to the tensioning motor 9 from a main compound woundgenerator l2 having a series coil l3 and a shunt coil l4. One terminalof the main generator I2 is connected to ground through the conductorl5, and the other passes from the series coil l3 through a switch l6,variable rheostats l1 and an ammeter II to the tensioning motor 9. Thistensioning motor preferably has a compound wound field consisting ofseries field coil l 3 and shunt field 20. From the motor 9 the currentpasses to ground through the main 2|.

The counter electro-motive force generated by the rotation of the motorarmature by the tensioning material is compensated by decreasing thecurrent through the main generator shunt field winding I l in proportionto the above electro-motive force. For this purpose the circuit throughthe shunt field winding ll leads through a conductor 22 to a shunt woundcompensating generator 23 having a shunt field coil 24, and returnsthrough a return conductor containing a variable resistance or rheostat26.

The armature of the compensating generator 23 is driven at a speedproportional to the speed of movement of the tensioned material and,therefore, at a speed proportional to or related to that of the motor 9.This may be accomplished by a number of diiferent mechanisms, dependingupon the particular conditions under which the apparatus may be used.For example, the armature of the compensating generator 23 may be drivenby the core I, or the means that rotate this core when a rotating coreis used, and as the speed of movement of the strip 3 is proportional tothe rotation of the core, the rotation of the armature 23 will be indirect relation or in proportion to the speed of rotation of thetensioning roller 8; or, if the reel 2 be rotated about the core, thearmature of the compensating generator 23 may be driven directly by thisrotating means or, the armature of the genera tor 23 may be geared orotherwise driven from the shaft of the tensioning roll 8, or of any ofthe idler rollers over which the strip is passed. These and other meansmay be employed to ensure a rotation of the armature of the compensatinggenerator 23 at a rate proportional to the rotation of the armature ofthe tensioning motor 9.

These various driving means are illustrated diagrammatically in Fig. 3,in which the armature of the motor 9 drives a shaft 21 carrying a pulley28, and the armature of the generator 23 is driven by a shaft 29carrying a drive pulley 30. The pulleys 28 and 30 are driven frompulleys 3i and 32, respectively, rotated from a common source as, forexample, a common shaft 33. Where a number of strands or strips aresupplied at equal speeds or to a common winding or wrapping device, theymay all be tensioned by current supplied from the generator l2 andcompensated by the compensator generator 23. For this purpose it is onlynecessary to duplicate the motor 9 as at 9', the various field coils l9and 20, connections 2| and the drive pulleys 28 and 3|, the latter ofwhich may be mounted on the common shaft 33.

It will be evident that the electro-motive force generated by thecompensating generator 23 may be adjusted by adjusting the resistance inthe field winding 24. For this purpose an adjustable rheostat 34 isprovided in this circuit. An additional or alternative control may beobtained by the variable rheostat 26.

In using the apparatus the variable resistance I! may be adjusted toobtain a desired torque, and the current required for this torque may beread in the ammeter la. The winding or movement of the tensionedmaterial may then take place and the variable rheostat 34 be adjusted tomaintain a constant current through the ammeter l8 and thus through themotor armature 9. This will provide a constant torque and a constanttension. If it is desired to decrease or increase the tension slightlywith increases of speeds, this may be accomplished by the compensatingrheostat 34.

Through the above invention, therefore, it is possible to maintain thetension constant throughout various changes in speed of the tensionedmaterial, or tocause controlled rises or drops in the tensioned materialwith changes in speed.

It will be understood that the specific examples of main generator andcompensating generator are given merely by way of example, and thatother main generators than a compound wound generator may be employed,and other compensating generators than a shunt wound generator may beemployed. These and other modifications may be made within the scope ofmy invention as defined in the appended claims.

What I claim is- 1. Tensioning apparatus which comprises a main compoundwound electric generator, a tensioning motor connected in circuit withsaid generator, tensioning means actuated by the passage of tensionedmaterial to rotate said motor against the torque imposed by current fromsaid generator, a compensating generator in the circuit of the shuntfield of said main generator, and means for driving said compensatinggenerator by said tensioning means to decrease the current in said shuntfield circuit with increase in the speed of said tensioned material.

2. Tensioning apparatus which comprises a main compound wound electricgenerator, a tensioning motor connected in circuit with said generator,tensioning means actuated by the passage of tensioned material to rotatesaid motor against the torque imposed by current from said generator, acompensating generator in the circuit of the shunt field of said maingenerator, means for driving said compensating generator by saidtensioning means to decrease the current in said shunt field circuitwith increase in the speed of said tensioned material, and an adjustablerheostat in the field of said compensating generator.

3. Tensioning apparatus which comprises a main compound wound electricgenerator, a tensioning motor connected in circuit with said generator,tensioning means actuated by the passage of tensioned material to rotatesaid motor against the torque imposed by current from said generator, ashunt wound compensating generator in the circuit of the shunt field ofsaid main generator, and means for driving said compensating generatorby said tensioning means to decrease the current in said shunt fieldcircuit with increase in the speed of said tensioned material.

4. Tensioning apparatus which comprises a main compound wound electricgenerator, a tensioning motor connected in circuit with said generator,tensioning means actuated by the passage of tensioned material to rotatesaid motor against the torque imposed by current from said generator, acompensating generator in the circuit of the shunt field of said maingenerator, means for driving said compensating generator by saidtensioning means to decrease the current in said shunt field circuitwith increase in the speed of said tensioned material, and a tensionadjusting rheostat in the circuit of said tensioning motor.

5. Tensioning apparatus which comprises a main compound wound electricgenerator, a tensioning motor connected in circuit with said generator,tensioning means actuated by the passage of tensioned material to rotatesaid motor against the torque imposed by current from said generator, acompensating generator in the circuit of the shunt field of said maingenerator, means for driving said compensating generator by saidtensioning means to decrease the current in said shunt field circuitwith increase in the speed of said tensioned material, an ammeter, and atension adjusting rheostat in the circuit of said tension motor.

6. Tensioning apparatus which comprises a main compound wound electricgenerator, a plurality of tensioning motors connected in parallelcircuits with said generator, tensioning means actuated by the passageof tensioned material to rotate said motors against the torque imposedby current from said generator, a compensating generator in the circuit01' the shunt field of said main generator, and means for driving saidcompensating generator by said tensloning means to decrease the currentin said shunt field circuit with increase in the speed of said tensionedmaterial.

7. Tensioning apparatus which comprises a main electric generator, atensioning motor connected in circuit with said generator, tensioningmeans actuated by the passage of the tensioned material to rotate saidmotor against the torque imposed by current from said generator, acompensating generator, and means for driving said compensatinggenerator by said tensioning means, said compensating generator beingelectrically connected to said main generator to decrease the generatedelectro-motive force of said main generator as the reverse rotation ofsaid tensioning motor increases.

8. Tensioning apparatus which comprises a main electric generator, atensioning motor connected in circuit with said generator, tensioningmeans actuated by the passage of the tensioned material to rotate saidmotor against the torque imposed by the current from said main electricgenerator, and means driven by the passage of the tensioned material togenerate a counter electromotive force to compensate for theelectro-motive force generated by said tensioning motor.

9. Tensioning apparatus which comprises a main electric generator, 9,tensioning motor connected in circuit with said generator, tensioning 25means actuated by the passage of the tensioned material to rotate saidmotor against the torque imposed by current from said enerator, andmeans driven by the passage of said tensioned material to compensate forthe eiectro-motive force generated by said motor when driven by saidtensioned material.

STANLEY F. FRENCH.

